On Tue, 2007-17-07 at 20:57 +0200, Christopher Arndt wrote:
> tinab schrieb:
> > I was hoping that there would be a way to generate the
> > python model code from an existing MySQL database,
I just did this with SQLalchemy and it was surprisingly easy. You will
probably want to go straight to the SA docs. All you need to do is make
a stub class and then use assign_mapper to map your stub class to the
existing table. You will probably also need to explicitly state the
relationship keys, which can be found in the SA docs in the advanced
data mapping section.
Here is an example from my project, please excuse the poor formatting:
# to load the table definition by introspecting the database
heard_table = Table('how_heard', metadata, autoload=True)
class Heard(object):
pass
assign_mapper(session.context, Heard, heard_table )
champions_table = Table('users', metadata, autoload=True)
class Champions(object):
pass
assign_mapper(session.context, Champions, champions_table )
# to load the table definition by introspecting the database
orders_table = Table('orders', metadata, autoload=True)
class Orders(object):
pass
assign_mapper(session.context, Orders, orders_table )
locations_table = Table('locations', metadata, autoload=True)
class Locations(object):
# attribute for total number of boxes ordered by a location
def _box_total(self):
count = 0
for order in self.orders:
if order.status == 'verified': count += order.quantity
return count
box_total = property( _box_total )
locations_dates_table = Table('locations_dates', metadata,
autoload=True )
class LocationDates(object):
pass
# LocationDates mapper
assign_mapper(session.context, LocationDates, locations_dates_table,
primary_key= [ locations_dates_table.c.location_id,
locations_dates_table.c.date ],
properties=dict(
locations=relation( Locations,
primaryjoin=and_(
locations_table.c.location_id==locations_dates_table.c.location_id ),
foreignkey=locations_dates_table.c.location_id ),
)
)
# because the old tables don't have foreign key defs, we need to
explicitly state them here
assign_mapper(session.context, Locations, locations_table,
properties=dict(
orders=relation(Orders,
primaryjoin=and_( orders_table.c.location_id==locations_table.c.location_id ),
foreignkey=orders_table.c.location_id ),
champion=relation( Champions,
primaryjoin=and_( locations_table.c.user_id==champions_table.c.user_id ),
foreignkey=locations_table.c.user_id ),
dates=relation( LocationDates,
primaryjoin=and_(
locations_table.c.location_id==locations_dates_table.c.location_id ),
foreignkey=locations_dates_table.c.location_id,
order_by=locations_dates_table.c.date ),
) )
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